ACS Biochemistry: – Questions With Well Detailed
Answers
Which amino acids in "a" would be charged at pH 7? Right Ans - Asp, Glu,
Arg, His, Lys
Which amino acids are negatively charged? Right Ans - Asp, Glu
Which amino acids are positively charged? Right Ans - Arg, His, Lys
Does myoglobin show cooperativity in O2 binding? If not, what structural
differences account for this? Right Ans - Myoglobin does not show
cooperativity because it is monomeric
Describe the structural changes in hemoglobin that allow for cooperative
binding of O2 Right Ans - Binding of O2 in one subunit causes a
conformational change in an adjacent subunit allowing O2 to bind
How are beta sheets stabilized in proteins? Right Ans - Hydrogen bonding
between peptide backbone groups
What is a transition state inhibitor (how does its structure compare to the
enzyme stubstrate?) how does its affinity for the enzyme compare to the
enzyme's substrate? Right Ans - Similar to the substrate; binds to the active
site with greater affinity than the substrate
would it be advantageous for these potential drugs to covalently bind to the
enzyme? why or why not? Right Ans - Not advantageous because the urea
cycle would shut down
From a practical standpoint, would it be advantageous for these potential
drugs to be less chemically stable than the substrate? Right Ans - No,
because of shelf life and time to reach target
In DNA, which bases hydrogen bond? Right Ans - A-T; G-C
In each base pair, how many hydrogen bonds are there? Right Ans - A-T=2;
G-C=3
, Which base-pair would require a higher temperature to destroy the hydrogen
bonds? Right Ans - G-C
Based on the mechanism of alkaline hydrolysis of RNA, why is DNA less
susceptible to alkaline hydrolysis? Right Ans - DNA lacks the 2' hydroxyl
group
What is the difference between a reducing and nonreducing sugar? Right
Ans - Reducing sugars have a free anomeric carbon that in the linear form can
reduce an oxidizing agent.
what is a reducing monosaccharide? Right Ans - fructose or glucose
what is a reducing disaccharide? Right Ans - lactose
what is a nonreducing dissacharide? Right Ans - sucrose
what is a nonreducing monosaccharide? Right Ans - all monosaccharides
are nonreducing
Why can't the peptide WYLVP be glycosylated in a glycoprotein? Right Ans
- because it does not contain N, S, or T which are sites of glycosation
(attachment of a carbohydrate)
Name three secondary messengers and what class of biomolecules they are
derived from Right Ans - cAMP-nucleotide; IP3-lipid; DAG-lipid
What reactions occur during stage one of glycolysis? Right Ans - aldolase,
F6P
What reactions occur during stage two of glycolysis? Right Ans - NADH
formed, 3PG formed
name an allosteric regulator that can decrease glycolysis by inhibiting PFK
Right Ans - ATP
What enzymes are unique to glycolysis? Right Ans - hexokinase, PFK,
pyruvate kinase
Answers
Which amino acids in "a" would be charged at pH 7? Right Ans - Asp, Glu,
Arg, His, Lys
Which amino acids are negatively charged? Right Ans - Asp, Glu
Which amino acids are positively charged? Right Ans - Arg, His, Lys
Does myoglobin show cooperativity in O2 binding? If not, what structural
differences account for this? Right Ans - Myoglobin does not show
cooperativity because it is monomeric
Describe the structural changes in hemoglobin that allow for cooperative
binding of O2 Right Ans - Binding of O2 in one subunit causes a
conformational change in an adjacent subunit allowing O2 to bind
How are beta sheets stabilized in proteins? Right Ans - Hydrogen bonding
between peptide backbone groups
What is a transition state inhibitor (how does its structure compare to the
enzyme stubstrate?) how does its affinity for the enzyme compare to the
enzyme's substrate? Right Ans - Similar to the substrate; binds to the active
site with greater affinity than the substrate
would it be advantageous for these potential drugs to covalently bind to the
enzyme? why or why not? Right Ans - Not advantageous because the urea
cycle would shut down
From a practical standpoint, would it be advantageous for these potential
drugs to be less chemically stable than the substrate? Right Ans - No,
because of shelf life and time to reach target
In DNA, which bases hydrogen bond? Right Ans - A-T; G-C
In each base pair, how many hydrogen bonds are there? Right Ans - A-T=2;
G-C=3
, Which base-pair would require a higher temperature to destroy the hydrogen
bonds? Right Ans - G-C
Based on the mechanism of alkaline hydrolysis of RNA, why is DNA less
susceptible to alkaline hydrolysis? Right Ans - DNA lacks the 2' hydroxyl
group
What is the difference between a reducing and nonreducing sugar? Right
Ans - Reducing sugars have a free anomeric carbon that in the linear form can
reduce an oxidizing agent.
what is a reducing monosaccharide? Right Ans - fructose or glucose
what is a reducing disaccharide? Right Ans - lactose
what is a nonreducing dissacharide? Right Ans - sucrose
what is a nonreducing monosaccharide? Right Ans - all monosaccharides
are nonreducing
Why can't the peptide WYLVP be glycosylated in a glycoprotein? Right Ans
- because it does not contain N, S, or T which are sites of glycosation
(attachment of a carbohydrate)
Name three secondary messengers and what class of biomolecules they are
derived from Right Ans - cAMP-nucleotide; IP3-lipid; DAG-lipid
What reactions occur during stage one of glycolysis? Right Ans - aldolase,
F6P
What reactions occur during stage two of glycolysis? Right Ans - NADH
formed, 3PG formed
name an allosteric regulator that can decrease glycolysis by inhibiting PFK
Right Ans - ATP
What enzymes are unique to glycolysis? Right Ans - hexokinase, PFK,
pyruvate kinase
